Alkylation of hydrocarbons



Patented Jan. 2, 1951 UNIT-Eo :STATE-s .PATENT Vorrrcr:

IJKYLATION '0F HYDROCARBON S Joe P enick, iWoodbnry, EN. J., :assigncr .to ISo curry-Vacuum Oil Company, Incorporated, .a.

corporation of `New York .fhydrccarbons and, Amore particularly,

Yimplication'Sep'teniber 28,1\948,1Seria1N0. 61,573 I4 Claims. (Cl. '260-683.4)

process -igenerally .involves `contacting parafiins :such-asiscbutane, with oleiins, such :as vn-butene, in .the ypresence of hydrogen .fluoride care being A.taken .that .a .considerable excess of isobutane .lbe used. ,In the .reaction vessel, wherein the materials .are contacted, .alkylation of paraiin .occurs lThe reaction mixtureof unreacted paraflin. hydrogen fluoride, valkylate .and carbon productsis taken ffrcm the reaction vessel .to a settler, wherein separation of two layers occurs. `The lower layer ispredominantlyhydro- .gen'fluorirc andthe Vupperlayer contains hydro carbons ated Withhydrcgen fluoride. From the settler, the upper layer .is :taken [to an other .hydron stripper "wherein hydrogen fluoride is removed 4overhead andthe hydrocarbons are introduced VVto a central portion of a fractionating column, gene'raljlydesignated a 'deisobutanizen Isobutane is'removed-'as an overhead product from the deisobutanizer and alkylate, `such a's-isooctane, is removed from the bottom thereof and is 'ta-ken to rother'fractionation means Jfor separation of desiredhydrocarbon fractions. VTogether with the 'isobutane removed overheadare propane, formed in thereaction, and minor amounts of'HF.

It has been yconsidered -nece'ssaryfor emcient operation to-'remove*substantially all of theisobutane -from lthe overhead product. This lhas :been realized.byintroducng'the overhead product into an intermediate section of the deiscbutanizer :andreturninga large portionof isobutane tothe :topoi' the deisobutanizer as redux. As will be freflgnized by those familiar with the art, :this 4conventional procedure involves a `considerable heat input to fthe i deisobutanizerso Las tc provide an eifective'separation acfiscbutane from thehydrocarbcn produc-t.

It'has .now been discovered `that the .large heat Y requirement ffor the deisobutanizer inthe fore- ;golng process ycan 'be `reduced 1appreciably. The

simplified process of this invention-comprises introduction of the 'hydrocarbon product from the 4-Hlibstripper directly Lto 4an upper'sectionfof the conduit I3 to HF stripper 'l 1l.

is taken from HF .stripper "|54 settler .6.

Y.2 deisobutanizer, and dispensing with isobutane recycle thereto.

'In order to facilitate 'description-of ythe process `contemplated herein, reference .is now V:made to 'the accompanying drawing, which showsfa'typical flow Adiagram of :a preferred Aarrangement lfor practicing the invention. For convenience 1in `i1 instr-ating the'invention, theliscussicn :of .the

`process is `directed specifically to alkylationrof `isollO butane `vvithfbutenes infthe `rnvesence of :concentrated HF. It will beunderstocdzof .'coursafthat the "invention is applicable also `to 4alkylation lci `other hydrocarbons in the Apresence 'oflI-IF.

shown in the dra-Wing, an .lisobiitanebutene charge in conduit l and HF in conduit..2=are `combined and introduced into alkylator l!` through inlet 3. Alkylator 4 maybe any suitable vessel resistant to corrosion by HF and provided with a mixing device, -such Aas one cr more jet-type and/cr perforated plate-'type inlets, bellies, or stirrers, capable of maintaining liquid hydrocarbcns and liquidHF in a state .ofintimatemixture. Therelative proportions of HF and hydrocarbons, and the conditions of temperature and pressure lin alkylator 4 are :discussed hereinbelow.

The liquid reaction rmixture inalkylator 4.is .taken through conduit 5 to settler wherein it separates into twophases or layers. The Vlower layer is predominantly HF with a small amount of .tar-like material. The `HFlaver is withdrawn from-settler 6 through conduit 'l with the aidof -purnp to HF regenerator 9. The tar-like material is rseparated in the regenerator 9 and is withdrawn through line ID. Regenerated HF' is taken as an `overhead through line Il and cooler \.l,2to line 1. Regenerated HF `and HFin line 'l are returned to the alkylator 'Il through-lines l2, Zand 3.

The upper layer in settler .i6 contains .alkylation products, excess ,isobutane propane, a small `amount of hydrocarbons boiling above isobu'tane, and a small amount of'HF, and lis taken through An overhead o`f IH Asaturated with a small amount `of vhydrocarbons Ithrough line i5, in and is recycled to A bottom productie taken .from .HF I4 throughline I'T and is lintroduced di- `which islocated a cooler I6,

stripper .rectly to an uppersection of deisobutanizer .`|8.

upper section of deisobutanizer I8 is roughly fractionated therein, without isobutane recycle for reux. Alkylate and some excess isobutane Vis removed from the deisobutanizer through line I9, and is thereafter further fractionated in suitable distillation equipment, not shown to provide alkylate fractions. An overhead comprising a major proportion of the isobutane, and propane, is takenfrom the deisobutanizer through conduit 20, in which is located cooler 2 I, to accumulator 22. The material, predominantly isobutane, in accumulator 22 is pumped through line 23 by means of pump 20 to recycle line 25. A portion of the material in line 23 may also be removed from the system through exit line 20.

To demonstrate the advantages of' the present process over conventional HF alkylation procedure, the following comparative examples are set forth in the table below. In the conventional procedure, the hydrocarbon reaction product from the HF stripper was introduced to a central section of the deisobutanizer, and isobutane was recycled to an upper section of the deisobutanizer to provide reflux. In the present process, the procedure described above and shown in the Ydrawing was followed.' To provide a proper comparative basis, the alkylation conditions were essentially the same, with the same quantity, 1000 barrels per day, of alkylate of the same quality, 90.5 octane number, being produced. Conditions of operation were: ratio of isobutane to butenes, 7:1; ratio of HF to hydrocarbon charge, 1:1; 87 per cent HF; temperature and pressure of alkylator, 90% F. and 120 pounds per square inch; contact time, 20 minutes.

Table Heat Rcquirements for Deisobutanizer (M B T Ul D I) Desobutanizer Fractionation.

Percent i-C4 in Overhead Plates in Doisobutanizer Conventional Process...

New Process l Expressed in million B. t. u. per day.

From the results shown in the table, it will be noted that the saving effected by the new process, in heat input to the deisobutanizer is 125 per cent, when the deisobutanizer contains the same number of plates (50). There is a saving of 150 per cent in heat input, even when the number of plates is increased to 80 in the conventional process.

Conventional alkylation conditions of temperature, pressure, time, isoparaifin-olen ratio and HF hydrocarbon ratio may be employed advantageously in the process contemplated herein. For example, the alkylation of isobutane with butenes may be carried out at temperatures between about F. and 150 F., preferably between about 40 F. and 140 F., at pressures at least sufciently high to keep the hydrocarbons and HF in the liquid phase, and with osobutane-butene ratios of between 2:1 to 15:1, preferably between about 6:1 and 10:1. Ratios of isobutane to butenes of at least 2:1 are essential since lower ratios tend to cause polymerization of the butenes with resultant decrease in yield of the alkylate product and/or excessive reaction between the butenes 'and .the primary alkylate product because of the relatively low ratios of isobutane to alkylate prodhydrous or may have a titratable acidity as low as '10% by weight, and is preferably between about 80 to 90%. The ratio of HF to hydrocarbon charge may be varied considerably, but most satisfactory results are obtained with an excess of HF. Generally, ratios of I-IF to hydrocarbon charge of at least 1:1 are used. Reaction time is advantageously maintained between about 1 minute and 60 minutes.

While the process of this invention is particularly well adapted for the production of Ca alkylates from isobutane and butenes, for example, the process is also suitable for other alkylation reactions. By way of illustration, Cr and Ca alkylates may be prepared from isobutane and mixtures of propylene and butenes; so also, C9 al- \kylates may be obtained by alkylation of isobutane with pentenes. In general, then the process is suitable for alkylation of alkylatable hydrocarbons, particularly low-boiling isoparafns, with alkylating agents, particularly low-boiling oleflns. As a further illustration of the process, cumene may be prepared herein by reaction of benzene with propylene.

I claim:

1. The continuous process for alkylating an alkylatable hydrocarbon with an alkylating agent in the presence of hydrogen fluoride, which comprises: contacting said alkylatable hydrocarbon with said alkylating agent in an alkylator under alkylating conditions to form a reaction mixture containing an alkylate of higher molecular weight than said alkylatable hydrocarbon; passingsaid reaction mixture to a settler wherein two phases are formed, one phase being essentially'hydrogen uoride and the other phase being a hydrocarbon phase containing a small amount of hydrogen fluoride, unreacted alkylatable hydrocarbon and said alkylate; separating said hydrogen uoride phase and recycling the same to said allrylator; strip.- ping said hydrocarbon phase of hydrogen fluoride; passing said stripped hydrocarbon phase to the top of a fractionator and fi'actiori'ating said hydrocarbon phase in the absence of reflux; withdrawing from the bottom of said fractionator a fraction containing said alkylate and a small quantity of said unreacted alkylatable hydrocarbon. withdrawing from the top of said fractionator a fraction containing the bulk of said unreacted alkylatable hydrocarbon and recycling said fraction.

2. The continuous process for alkylating an isoparain with an olen in the presence of hydrogen fluoride, which comprises: contacting said isoparain with said olen and hydrogen fluoride in an alkylator under allylating conditions to form a reaction mixture containing isoparains of higher molecular weight than said isoparain reactant; passing said reaction mixture to a settler wherein two phases are formed, one phase being essentially hydrogen iiuoride and the other phase being a hydrocarbon phase containing a smallV amount of hydrogen fluoride, unreacted isoparaiin and said higher molecular weight isoparaflins; separating said hydrogen fluoride phase and recycling the same to said alkylator; stripping said hydrocarbon phase of hydrogen fluoride; passing said stripped hydrocarbon phase to the top of a fractionator and fractionating said hydrocarbon phase in the absence of reflux; withdrawing from the bottom of said fractionator a fraction containing said higher molecularweight isoparaiiins and a small quantity of said-unreaoted isoparain; withdrawuct in the reaction mixture. The HF may be anin g from the topof said fractionator a fraction containing the bulk of said unreacted isoparain and recycling said fraction.

3. The process of claim 2 in which said isoparafn is a low-boiling isoparaiiin and said olefin is a low-boiling olen.

4. The continuous process for alkylating isobutane with butenes in the presence of hydrogen fluoride, which comprises: contacting said isobutane with butenes and hydrogen fluoride in an alkylator under alkylating conditions to form a reaction mixture containing isoparains of higher molecular weight than said isobutane; passing said reaction mixture to a settler wherein two phases are formed, one phase being essentially hydrogen fluoride and the other phase being a hydrocarbon phase containing a small amount of hydrogen iiuoride, unreacted isobutane and said higher molecular Weight isoparafiins; separating said hydrogen fluoride phase and recycling the same to said alkylator; stripping said hydrocarbon phase of hydrogen fluoride; passing said stripped 2 hydrocarbon phase to the top of a fractionator and fractionating said hydrocarbon phase in the absence of isobutane rciiux; withdrawing from he bottom of said fractionator a fraction containing said higher molecular Weight isoparafns and a small quantity of said unreacted isobutane; withdrawing from the top of said fractionator a fraction containing the bulk of said unreacted isobutane and recycling said fraction.

JOE E. PENICK.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,392,962 Abrams et al. Jan. l5, 1946 2,397,085 Baedeker et al. Mar. 26, 1946 2,444,316 Vautrain June 29, 1948 2,448,092 Gibson Aug. 31, 1948 Certificate of Correction Patent No. 2,536,515 January 2, 1951 JOE E. PENoK It s hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 3, line 311, for 90% read 90; line 52, 'for 150 read 105; line 65, for osobutanebutene read z'sobntnne-bntene; and that the said Letters Patent should he read as Corrected above, so that the same may conformI to the record of the case in the Patent Office.

Signed and sealed this 15th day of May, A. D. 1951.

[SEAL] THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

1. THE CONTINUOUS PROCESS FOR ALKYLATING AN ALKYLATABLE HYDROCARBON WITH AN ALKYLATING AGENT IN THE PRESENCE OF HYDROGEN FLUORIDE, WHICH COMPRISES: CONTACTING SAID ALKYLATABLE HYDROCARBON WITH SAID ALKYLATING AGENT IN AN ALKYLATOR UNDER ALKYLATING CONDITIONS TO FORM A REACTION MIXTURE CONTAINING AN ALKYLATE OF HIGHER MOLECULAR WEIGHT THAN SAID ALKYLATABLE HYDROCARBON; PASSING SAID REACTION MIXTURE TO A SETTLER WHEREIN TWO PHASES ARE FORMED, ONE PHASE BEING ESSENTIALLY HYDROGEN FLUORIDE AND THE OTHER PHASE BEING A HYDROCARBON PHASE CONTAINING A SMALL AMOUNT OF HYDROGEN FLUORIDE, UNREACTED ALKYLATABLE HYDROCARBON AND SAID ALKYLATE; SEPARATING SAID HYDROGEN FLUORIDE PHASE AND RECYCLING THE SAME TO SAID ALKYLATOR; STRIPPING SAID HYDROCARBON PHASE OF HYDROGEN FLUORIDE; PASSING SAID STRIPPED HYDROCARBON PHASE TO THE TOP OF A FRACTIONATOR AND FRACTIONATING SAID HYDROCARBON PHASE IN THE ABSENCE OF REFLUX; WITHDRAWING FROM THE BOTTOM SAID FRACTIONATOR A FRACTION CONTAINING SAID ALKYLATE AND A SMALL QUANTITY OF SAID UNREACTED ALKYLATABLE HYDROCARBON, WITHDRAWING FROM THE TOP OF SAID FRACTIONATOR A FRACTION CONTAINING THE BULK OF SAID UNREACTED ALKYLATABLE HYDROCARBON AND RECYCLING SAID FRACTION. 